package cn.redsoft.wechatapi.common.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import cn.redsoft.wechatapi.common.Consts;

/**
 * 签名工具类<br>
 * <a href='http://blog.csdn.net/lyq8479/article/details/8944988'>参见柳峰的博客</a>
 * 
 * @author LiuFeng
 *
 */
public class SignatureUtil {
	// 与接口配置信息中的Token要一致
	private static String token = Consts.TOKEN;

	/**
	 * 验证签名
	 * 
	 * @param signature
	 * @param timestamp
	 * @param nonce
	 * @return
	 */
	public static boolean checkSignature(String signature, String timestamp,
			String nonce) {
		String[] arr = new String[] { token, timestamp, nonce };
		Arrays.sort(arr);
		StringBuilder content = new StringBuilder();
		for (int i = 0; i < arr.length; i++) {
			content.append(arr[i]);
		}
		MessageDigest md = null;
		String tmpStr = null;

		try {
			md = MessageDigest.getInstance("SHA-1");
			byte[] digest = md.digest(content.toString().getBytes());
			tmpStr = byteToStr(digest);
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}

		content = null;
		return tmpStr != null ? tmpStr.equals(signature.toUpperCase()) : false;
	}

	private static String byteToStr(byte[] byteArray) {
		String strDigest = "";
		for (int i = 0; i < byteArray.length; i++) {
			strDigest += byteToHexStr(byteArray[i]);
		}
		return strDigest;
	}

	private static String byteToHexStr(byte mByte) {
		char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A',
				'B', 'C', 'D', 'E', 'F' };
		char[] tempArr = new char[2];
		tempArr[0] = Digit[(mByte >>> 4) & 0X0F];
		tempArr[1] = Digit[mByte & 0X0F];

		String s = new String(tempArr);
		return s;
	}

}
